To explore induced islet neogenesis in the liver as a strategy for the treatment of diabetes, we used helper-dependent adenovirus (HDAD) to deliver the pancreatic duodenal homeobox-1 gene (Ipf1; also known as Pdx-1) to streptozotocin (STZ)-treated diabetic mice. HDAD is relatively nontoxic as it is devoid of genes encoding viral protein. Mice treated with HDAD-Ipf1 developed fulminant hepatitis, however, because of the exocrine-differentiating activity of Ipf1. The diabetes of STZ mice was partially reversed by HDAD-mediated transfer of NeuroD (Neurod), a factor downstream of Ipf1, and completely reversed by a combination of Neurod and betacellulin (Btc), without producing hepatitis. Treated mice were healthy and normoglycemic for the duration of the experiment (>120 d). We detected in the liver insulin and other islet-specific transcripts, including proinsulin-processing enzymes, beta-cell-specific glucokinase and sulfonylurea receptor. Immunocytochemistry detected the presence of insulin, glucagon, pancreatic polypeptide and somatostatin-producing cells organized into islet clusters; immuno-electron microscopy showed typical insulin-containing granules. Our data suggest that Neurod-Btc gene therapy is a promising regimen to induce islet neogenesis for the treatment of insulin-dependent diabetes.

Insulin-producing cells normally occur only in the pancreas and thymus. Surprisingly, we found widespread insulin mRNA and protein expression in different diabetic mouse and rat models, including streptozotocin-treated mice and rats, ob͞ob mice, and mice fed high-fat diets. We detected in diabetic mice proinsulinand insulin-positive cells in the liver, adipose tissue, spleen, bone marrow, and thymus; many cells also produced glucagon, somatostatin, and pancreatic polypeptide. By in situ nucleic acid hybridization, diabetic, but not nondiabetic, mouse liver exhibited insulin transcript-positive cells, indicating that insulin was synthesized by these cells. In transgenic mice that express GFP driven by the mouse insulin promoter, streptozotocin-induced diabetes led to the appearance of GFP-positive cells in liver, adipose tissue, and bone marrow; the fluorescent signals showed complete concordance with the presence of immunoreactive proinsulin. Hyperglycemia produced by glucose injections in nondiabetic mice led to the appearance of proinsulin-and insulin-positive cells within 3 days. Bone marrow transplantation experiments showed that most of the extrapancreatic proinsulin-producing cells originated from the bone marrow. Immunoreactive proinsulin-and insulin-positive cells were also detected in the liver, adipose tissue, and bone marrow of diabetic rats, indicating that extrapancreatic, extrathymic insulin production occurs in more than one species. These observations have implications for the regulation of insulin gene expression, modulation of selftolerance by insulin gene expression, and strategies for the generation of insulin-producing cells for the treatment of diabetes.pancreatic islets ͉ hyperglycemia ͉ ob͞ob ͉ obesity ͉ bone marrow transplantation I nsulin is normally produced in highly specialized cells of the endocrine pancreas. The tissue-specific expression of insulin is tightly regulated at the transcriptional level, and the major regulatory elements are located in the 5Ј flanking region of the insulin gene (1). Insulin expression is specific to ␤ cells in the pancreatic islets, although proinsulin has also been detected in the fetal and postnatal thymus and spleen͞lymphoid tissues (2, 3), a pattern of promiscuous expression of normally tissuerestricted ''peripheral'' proteins in these tissues (4, 5). Immunoreactivity to insulin plays a key role in autoimmune diabetes in NOD mice (6, 7) and in type 1 diabetes in humans (7); expression of minute amounts of insulin in the thymus is believed to be important in the induction of tolerance to insulin and other ''self-antigens '' (8-11). In this study, we found insulin gene transcription and protein expression in multiple tissues outside the pancreas and thymus in mice and rats with diabetes. The widespread occurrence of extrapancreatic, extrathymic insulin gene products in diabetic animals is surprising; it suggests that we should revise our thinking on the regulation of insulin gene expression, the mechanism of immune tolerance to insulin, the pathophysi...

Diabetic neuropathy is the most common microvascular complication of diabetes. Here we show that, in streptozotocin-induced diabetic rodents with neuropathy, a subpopulation of bonemarrow-derived cells marked by proinsulin expression migrates to and fuses with neurons in the sciatic nerve and dorsal root ganglion (DRG), resulting in neuronal dysfunction and accelerated apoptosis. The absence or presence of proinsulin expression, which identifies the fusion cells, and not the disease state (nondiabetic vs. diabetic) of the rats from which the DRG neurons are isolated determines whether the DRG neurons show normal or abnormal calcium homeostasis and apoptosis. These results suggest that bone-marrow-derived cells may play an important role in the pathogenesis of diabetic complications.diabetes ͉ diabetic complications ͉ dorsal root ganglion ͉ amputations ͉ bone marrow transplantation

No abstract

No abstract

To investigate if intracellular glycerol content plays a role in the regulation of insulin secretion in pancreatic ␤ cells, we studied the expression of the glycerol channels, or aquaglyceroporins, encoded by the aquaporin 3 (Aqp3), Aqp7, and Aqp9 genes in mouse islets. We found expression of Aqp7 only, not that of Aqp3 or Aqp9, in the endocrine pancreas at both the mRNA (by reverse transcription-PCR) and protein (by immunohistochemistry) levels. Immunohistochemistry revealed a complete overlap between insulin and Aqp7 immunostaining in the pancreatic islet. Inactivation of Aqp7 by gene targeting produced viable and healthy mice. Aqp7 ؊/؊ mice harbored an increased intraislet glycerol concentration with a concomitant increase of the glycerol kinase transcript level and enzyme activity. The islet triglyceride content in the Aqp7 ؊/؊ mice was also increased compared to that in the Aqp7 ؉/؉ mice. Interestingly, Aqp7 ؊/؊ mice displayed reduced ␤-cell mass and insulin content but increased insulin-1 and insulin-2 mRNAs. The reduction of ␤-cell mass in Aqp7 ؊/؊ mice can be explained at least in part by a reduction in cell proliferation through protein kinase C and the c-myc cascade, with a reduction in the transcript levels of these two genes. Concomitantly, there was a decreased rate of apoptosis, as reflected by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and caspase 3 and Bax expression in Aqp7 ؊/؊ mice. Compared with Aqp7 ؉/؉ islets, islets isolated from Aqp7mice secreted insulin at a higher rate under basal low-glucose conditions and on exposure to a high (450 mg/dl) glucose concentration. Aqp7 ؊/؊ mice exhibited normal fasting blood glucose levels but elevated blood insulin levels. Their plasma glucose response to an intraperitoneal (i.p.) glucose tolerance test was normal, but their plasma insulin concentrations were higher than those of wild-type mice during the 2-h test. An i.p. insulin tolerance test showed similar plasma glucose lowering in Aqp7 ؊/؊ and Aqp7 ؉/؉ mice, with no evidence of insulin resistance. In conclusion, we found that pancreatic ␤ cells express AQP7, which appears to be a key regulator of intraislet glycerol content as well as insulin production and secretion.Glucose is the most important nutrient that regulates insulin secretion (21). In addition to its key role in insulin secretion, plasma glucose also regulates ␤-cell mass; in insulin-resistant states, the ␤-cell mass increases to provide sufficient insulin to keep the plasma glucose concentration in check. Therefore, glucose appears to play dual roles as a stimulus both for acute insulin secretion and for a compensatory increase in ␤-cell mass (8). Unlike glucose, glycerol, a triose sugar, has no apparent effect on insulin secretion (37, 39), though a closely related metabolite, glyceraldehyde, has a potent effect (1, 2). One reason that glycerol does not function as a signal for insulin secretion is that it appears not to be metabolized by pancreatic ␤ cells (37). Induced overexpression of glycerol kina...

Phakic IOL implantation may offer significant vision-related quality-of-life advantages (eg, fewer activity limitations and symptoms and better appearance and satisfaction with correction) over wavefront-guided LASIK for myopia in the long term. Moreover, refractive surgery may provide a better quality of life in younger patients.

Diabetic peripheral neuropathy is a major chronic diabetic complication. We have previously shown that in type 1 diabetic streptozotocin-treated mice, insulin- and TNF-α co-expressing bone marrow-derived cells (BMDCs) induced by hyperglycemia travel to nerve tissues where they fuse with nerve cells, causing premature apoptosis and nerve dysfunction. Here we show that similar BMDCs also occur in type 2 diabetic high-fat diet (HFD) mice. Furthermore, we found that hyperglycemia induces the co-expression of insulin and TNF-α in c-kit+Sca-1+lineage+ (KSL) progenitor cells, which maintain the same expression pattern in the progeny, which in turn participates in the fusion with neurons when transferred to normoglycemic animals.